In a small clinical trial, a therapeutic vaccine from Pennsylvania company Inovio Pharmaceuticals showed promise for treating precancerous cervical lesions in women with HPV.

Most cases of cervical cancer are caused by two high-risk strains of HPV, or human papillomavirus: HPV 16 and 18. The experimental vaccine, known as VGX-3100, is designed to encourage the body’s immune system to get rid of cells that have been altered by these HPV strains. Using a technique similar to gene therapy, the vaccine inserts DNA into the patient’s cells, which then encourages an immune response against cells that have been altered by HPV.

In the recent study, published in the journal Science Translational Medicine, 18 women were given three doses of the vaccine. Fourteen women showed a robust cellular response to the vaccine. That is, the vaccine stimulated the production of killer T-cells, immune system cells that attack invaders, including precancerous cervical cells affected by HPV.

“Our immune system is capable of protecting us from millions of pathogens,” J. Joseph Kim, president and chief executive of Inovio Pharmaceuticals, told the New York Times. “We want to use the existing hardware in our immune system, but use better software to train our immune system to fight off disease.”

HPV is the most common sexually transmitted infection in the U.S.; the CDC reports that at least 50% of sexually active men and women get it at some point in their lives. In 90% of cases, the body naturally clears HPV on its own within two years. But if infection persists, some strains of HPV can cause genital warts, while others can lead to cancer, including cervical cancer and cancers of the vulva, vagina, penis, anus and throat.

The new study was a preliminary study designed to assess safety, not efficacy, so further research needs to be done to figure out whether the experimental vaccine can actually eliminate precancerous lesions. If the research continues to hold up, however, it could potentially help thousands of women who are at risk of developing cervical cancer each year.

“For the 300,000 women who are conservatively estimated to be undergoing surgical procedures to treat precancerous cervical lesions each year in the U.S., this raises the hope of someday having a nonsurgical approach to manage this problem,” Dr. Mark Einstein, a gynecologic oncologist and director of clinical research of women’s health at Montefiore Medical Center in New York City, told HealthDay. “That would have to be the Holy Grail.”

The experimental vaccine is not related to preventive vaccines like Merck’s Gardasil or GlaxoSmithKline’s Cervarix, which are used to prevent HPV infection in the first place.

Researchers are currently testing the new vaccine in 150 additional women in a Phase 2 trial, the results of which are expected in 2013.